Collapsible or folding portable structures for cautionary, warning or alert purposes have been employed or proposed wherein a plurality of substantially rigid legs are hingedly connected at one end and biased to expand the opposite ends away from each other. Examples include U.S. Pat. No. 5,199,375 and U.S. patent application Publication No. 2006/0225319. The legs of such structures are generally covered with a flexible material such as canvas, plastic or fabric, which bears a warning message. In a deployed position, the structure rests on the ends of the legs that have been expanded away from each other, forming a pyramidal structure.
The biasing means within such structures is unsatisfactory. In U.S. Pat. No. 5,199,375, for example, torsional coil springs have ends each inserted into the ends of the tubular stays or legs, with the ends of two different springs being received by each leg and each spring having an end inserted in two adjacent legs. Such a biasing scheme suffers from the potential for an end of one or more springs to become dislodged from the leg into which that spring end was inserted, by coming out of the leg's end longitudinally, by the material of the tubular leg splitting, or as a result of some other circumstance. The different forces placed on the tubular leg by springs urging the leg in different directions may, for example, induce material fatigue and splitting of the leg at the end in which the spring ends are inserted. In such situations, an imbalance arises in the biasing and the structure may not deploy properly. In addition, failure of one of the springs may result in the biasing forces of the remaining two springs to cause the structure to deploy incorrectly.
The device disclosed in U.S. Patent Application Publication No. 2006/0225319 utilizes a biasing spring moving a spreader mechanism along a central rod, and is thus complicated and more expensive to manufacture and involves more parts that may malfunction. Thus, the existing biasing mechanisms for self-standing portable structures used to provide information, such warnings, advertisements, and/or general content, have not been successful in providing a simple structure that is inexpensive to manufacture, compact for storage and transportation, lightweight and easy to carry, quick and easy to erect, and quick and easy to collapse.
There is, therefore, a need in the art for an improved portable information sign device.